Gestational Diabetes - WebMD
Gestational diabetes is a condition characterized by high blood glucose (sugar) levels that is first recognized during pregnancy. The condition occurs in approximately 4% of all pregnancies.
What Causes Gestational Diabetes?
Almost all women have some degree of impaired glucose intolerance during pregnancy as a result of hormonal changes that occur during pregnancy. That means that their blood sugar may be higher than normal, but not high enough to have diabetes. During the later part of pregnancy (the third trimester), these hormonal changes place pregnant woman at risk for gestational diabetes.
During pregnancy, increased levels of certain hormones made in the placenta (the organ that connects the baby by the umbilical cord to the uterus) help shift nutrients from the mother to the developing fetus. Other hormones are produced by the placenta to help prevent the mother from developing low blood sugar. They work by stopping the actions of insulin.
Over the course of the pregnancy, these hormones lead to progressive impaired glucose intolerance (higher blood glucose levels). To try to decrease the glucose levels, the body makes more insulin to shuttle glucose into cells.
Usually the mother's pancreas is able to produce more insulin (about three times the normal amount) to overcome the effect of the pregnancy hormones on glucose levels. If, however, the pancreas cannot produce enough insulin to overcome the effect of the increased hormones during pregnancy, glucose levels will rise, resulting in gestational diabetes.
What Are the Complications of Gestational Diabetes?
Diabetes in a pregnant woman can affect the developing baby throughout the pregnancy. In early pregnancy, maternal diabetes can result in birth defects and an increased rate of miscarriage. Many of the birth defects that occur affect major organs such as the brain and heart.
During the second and third trimester, maternal diabetes can lead to over-nutrition and excess growth of the baby. Having a large baby increases risks during labor and delivery. For example, large babies often require caesarean deliveries and if he or she is delivered vaginally, they are at increased risk for trauma to their shoulder.
In addition, when fetal over-nutrition occurs and hyperinsulinemia results, the baby's blood glucose can drop very low after birth, since it won't be receiving the high blood glucose from the mother.
However, with proper treatment, you can deliver a healthy baby despite having gestational diabetes.
Who Is at Risk for Gestational Diabetes?
The following factors increase the risk of developing diabetes during pregnancy:
Being overweight prior to becoming pregnant (if you are 20% or more over your ideal body weight).
Being a member of a high risk ethnic group (Hispanic, black, Native American, or Asian).
Having glucose in your urine.
Impaired glucose tolerance or impaired fasting glucose (blood glucose levels are high, but not high enough to be diabetes).
Family history of diabetes (if your parents or siblings have diabetes).
Previously giving birth to a baby over 9 pounds.
Previously giving birth to a stillborn baby.
Having gestational diabetes with a previous pregnancy.
Having too much amniotic fluid (a condition called polyhydramnios).
Many women who develop gestational diabetes have no known risk factors.
How Is Gestational Diabetes Diagnosed?
High risk women should be screened for gestational diabetes as early as possible during their pregnancies. All other women will be screened between the 24th and 28th week of pregnancy.
To screen for gestational diabetes, you will take a test called the oral glucose tolerance test. This test involves quickly drinking a sweetened liquid, which contains 50g of glucose. The body absorbs this glucose rapidly, causing blood glucose levels to rise within 30-60 minutes. A blood sample will be taken from a vein in your arm 1 hour after drinking the solution. The blood test measures how the glucose solution was metabolized (processed by the body).
A blood glucose greater than or equal to 140mg/dL is recognized as abnormal. If your results are abnormal based on the oral glucose tolerance test, another test will be given after fasting for several hours.
In women at high risk of developing gestational diabetes, a normal screening test result is followed up with another screening test at 24-28 weeks for confirmation of the diagnosis.
Learn more about diagnosing diabetes.
How Is Gestational Diabetes Managed?
Gestational diabetes is managed by:
Monitoring blood glucose levels four times per day (before breakfast and 2 hours after meals. Monitoring blood glucose before all meals may also become necessary.)
Monitoring urine for ketones (an acid that indicates your diabetes is not under control).
Following specific dietary guidelines as instructed by your doctor. You'll be asked to distribute your calories evenly throughout the day.
Exercising after obtaining your health care provider's permission.
Monitoring weight gain.
Taking insulin, if necessary. Insulin is currently the only diabetes medication used during pregnancy.
How Do I Monitor My Blood Glucose Levels?
Testing your blood glucose at certain times of the day will help determine if your exercise and eating patterns are keeping your blood glucose levels in control, or if you need extra insulin to protect your developing baby. Your health care provider will ask you to maintain a daily food record and ask you to record your home glucose levels.
Testing your blood glucose involves pricking your finger with a lancet device (a small, sharp needle), putting a drop of blood on a test strip, using a blood glucose meter to display your results, recording the results in a log book and then disposing the lancet and strips properly (in a "sharps" container or a hard plastic container, such as a laundry detergent bottle).
Bring your blood glucose readings with you to your doctor appointments so your doctor can evaluate how well your glucose levels are controlled and determine if changes need to be made to your treatment plan.
Your health care provider will show you how to use a glucose meter. He or she can also tell you where to get a meter. You may be able to borrow it from your hospital, as many hospitals have loaner meter programs for women with gestational diabetes.
The goal of monitoring is to keep your blood glucose as close to normal as possible. The ranges include:
Time of Test Target Blood Glucose Reading
Before breakfast plasma below 105; whole blood below 95
2 Hours After Meals plasma below 130; whole blood below 120
Insulin treatment is started if above levels are not maintained.